Eureka! I just got my headstock back together and on my SS. Did a tear down and complete cleaning; replaced both bearings on the drive sleeve, and put a new two bearing quill on, in addition to replacing the wedge locks. After having to reorder my re-assembly a couple of times so that I put it back together in the right order it runs as slick as Nick's. I used a couple of 18" long 1x's and rope to compress the spring on the movable motor sheeve. By already having two lengths of rope knotted in loops the right length to hold the top board (the one with the hole to go over the motor shaft) to the bottom board under the headstock I was able to push down on the top board, put one rope at a time over the ends of the boards while holding down the top board to keep the spring compressed. Once I had both ropes on, it was a simple matter to put the snap ring back in place to secure the spring.
A friend with a press helped me pull the old bearings off and press on the new ones. I noticed that my drive sleeve is one that has an allen screw in the center portion of the drive and after removing one of the bearings we loosened the locking allen screw and slid the center of the drive sleeve over enough to get the arms of the gear puller over the other bearing.
This experience did help to much better understand the inner workings of the headstock and made me appreciate the engineering and craftsmanship of the machine. If I can help others with questions about this procedure I would be more than happy to do so. Steve